First measurements of ηc decaying into K+K−2(π+π−) and 3(π+π−)

The decays of ηc to K+K−2(π+π−) and 3(π+π−) are observed for the first time using a sample of 5.8×107J/ψ events collected by the BESII detector. The product branching fractions are determined to be B(J/ψ→γηc)⋅B(ηc→K+K−π+π−π+π−)=(1.21±0.32±0.24)×10−4, B(J/ψ→γηc)⋅B(ηc→K∗0K¯∗0π+π−)=(1.91±0.64±0.48)×10−4, and B(J/ψ→γηc)⋅B(ηc→π+π−π+π−π+π−)=(2.59±0.32±0.47)×10−4. The upper limit for ηc→ϕπ+π−π+π− is also obtained as B(J/ψ→γηc)⋅B(ηc→ϕπ+π−π+π−)<6.03×10−5 at the 90% confidence level.